Group-III Nitrides such as GaN, AlN and AlGaN alloys are very important materials in the fabrication of optoelectronics (e.g. solid state lighting), laser diodes, and high power electronics. One method used to deposit Group-III nitride films is hydride vapor phase epitaxy (HVPE). In conventional HVPE, a gaseous hydrogen halide or halogen reacts with the Group-III metal to create a metal halide which then reacts with a nitrogen precursor to form the Group-III metal nitride. The reaction typically involves the high temperature vapor phase reaction between one or more metallic chlorides and ammonia (NH3). HVPE has significant advantages over other deposition methods. These advantages include high film growth rates, excellent material characteristics, flexible growth conditions, good reproducibility, simplicity in hardware and low cost of ownership. However, one of the difficulties with HVPE is achieving good within-chamber thickness uniformity of the Group-III nitride film.